Methods and apparatus for optical wireless communication

ABSTRACT

Methods and apparatus for optical wireless communication. In one embodiment, a wireless optical video system in which video content (e.g., DVI or HDMI) is transmitted wirelessly between a digital video source and a display device. This wireless optical communication is accomplished using a laser, encoded with the digital video data, directed from an optical transmitter to an optical receiver. In another embodiment, the data to be communicated includes high-definition video content.

FIELD OF THE INVENTION

The present invention relates generally to optical wirelesscommunication, and in particular to wireless optical delivery of a videosignal.

BACKGROUND

The preferred consumer digital video interfaces are High DefinitionMultimedia Interface (HDMI) and Digital Visual Interface (DVI). DVI iscommonly used by PC equipment to drive digital video displays. DVItypically supports 24-bit RGB at video rates up to 165 MHz. A DVI driveraccepts 24-bit RGB data and serializes it into three serial channels.The video clock is added as a fourth channel. As the RGB data isserialized, it is encoded using an 8b/10b encoding scheme calledTransition Minimized Differential Signaling (TMDS). HDMI is backwardscompatible with DVI. It supports alternate (non-RGB) color spaces andincludes the ability to carry digital audio.

As with DVI, HDMI data is encoded to represent active video periods andcontrol periods. In addition, HDMI includes a third entity called a DataIsland. Data Islands are used to communicate additional data during theblanking interval. For example, data islands are used to send digitalaudio data in HDMI.

Data delivered using a DVI or HDMI interface may be encrypted usingHigh-Bandwidth Digital-Content Protection (HDCP). Implementation of HDCPrequires a set of unique secret device keys. During authentication, thereceiver will only receive content once it demonstrates knowledge of thekeys. Furthermore, to prevent eavesdropping and stealing of the data,the transmitter and receiver will generate a shared secret value that isconsistently checked throughout the transmission. Once authentication isestablished, the transmitter encrypts the data and sends it to thereceiver for decryption.

Heretofore, DVI/HDMI data has only been deliverable using hard wires dueat least in part to the way the data source and the display device needto communicate with each other. However, it may be desirable for aconsumer to want to place a display device (such as a flat-paneltelevision) on a wall opposite from the video source (e.g., receiver orDVD player). In this case, the consumer would typically be required topurchase and install DVI cabling from the video source to the display.However, this may be both costly and present difficult installationissues.

A wireless radio frequency (RF) system could be used between a videosource and a display device. However, there may be numerous reasons forpreferring a wireless optical configuration between a digital videosource and a display device. For example, the hardware required for anoptical wireless signal may be less complex than a RF system. Moreover,a wireless optical solution is more secure since it will not penetratewalls as with an RF system.

Therefore, a wireless optical system which eliminates the need forcabling between a digital video source and a digital video sink may bedesirable.

SUMMARY

Methods and apparatus for optical wireless communication are disclosed.In one embodiment, a system includes a video data source having a sourceoutput, an optical wireless transmitter to receive video data from thesource output and encode the video data into a laser beam, and anoptical wireless receiver to receive the laser beam and to extract thevideo data there from. The method further includes a display devicehaving a destination input, wherein the display device receives thevideo data from the optical wireless receiver and presents a videodisplay based on said video data.

Other aspects, features, and techniques of the invention will beapparent to one skilled in the relevant art in view of the followingdetailed description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is one embodiment of a system level diagram for a digital videosystem in accordance with the principles of the invention;

FIG. 2 is one embodiment of an optical transmitter capable of carryingout one or more aspect of the invention;

FIG. 3 is one embodiment of an optical receiver capable of carrying outone or more aspect of the invention;

FIG. 4 is a more detailed diagram of the transmitter circuit of FIG. 2;

FIG. 5 is one embodiment of an electro-optical interface between theoptical transmitter of FIG. 2 and the optical receiver of FIG. 3;

FIG. 6 is a more detailed diagram of the receiver circuit of FIG. 2; and

FIG. 7 is one embodiment of a control-channel system implemented inaccordance with the principles of the invention.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

One aspect of the invention is to provide a wireless optical videosystem in which video content (e.g., DVI or HDMI) is wirelesslytransmitted between a digital video source and a display device. In oneembodiment, this wireless optical communication is accomplished using alaser, encoded with the digital video data, directed from an opticaltransmitter to an optical receiver. In another embodiment, the data tobe communicated includes high-definition video content.

Another aspect of the invention is to use a collimating lens to focus awireless optical signal onto the focusing lens of a receiver. While inone embodiment, the laser beam to be transmitted is betweenapproximately ¼ inch to approximately ½ inch, it should equally beappreciated that the beam may equally have a thicker or thinnerdiameter.

Another aspect of the invention is to provide the video data to thedisplay at the same resolution and with the same video clock speed asthat of the video source. For example, HDMI and DVI provide a mechanismfor the video source to query the video sink as to what video formatsare supported. Once queried, the video source may select the “best”video format for sending video data to the display. This selected videoformat may then be passed from the video source, through a wirelessoptical link, and on to a display device.

In one embodiment, the invention also makes use of a control channelcommunication system to enable DVI and HDMI content to be transmittedwirelessly. Heretofore, DVI/HDMI data has only been deliverable usinghard wires given that the data source and the display device arerequired to actively communicate with each other. In one embodiment,this control channel communication system is provided by a low data-rate2.4 GHz RF link. It should further be appreciated that a control-channelcommunication system may be implemented with an alternate technology,such as for example an Infrared optical communication link.

While much of the following description is in terms of HDMI/DVI contentand system components, it should equally be appreciated that theprinciples of the invention are not limited and such, and may be appliedto any other type of video content, such as serial digital interface(SDI) and high-definition serial digital interface (HD SDI).

Referring now to FIG. 1, depicted is a digital video system 100 usableto implement one or more aspects of the invention. As depicted in FIG.1, a video source 110 may be coupled to an optical transmitter 120. Inone embodiment, the video source is an HDMI/DVI video source, such as anATSC tuner, DVD player, etc. In another embodiment, the video source 110is a high-definition video source. In still another embodiment, thevideo source 110 may be any known video source (e.g., HD SDI, 1080i,720p, 480p, 480i, standard definition, etc.). Moreover, the signalprovided to the optical transmitter 120 by the video source 110 may beencrypted with a copyright protection protocol, such as High-bandwidthDigital Content Protection (HDCP).

Continuing to refer to FIG. 1, in one embodiment the video source 110provides video data to the optical transmitter 120, which in turnprovides a wireless optical signal 130 to optical receiver 140. As willbe described in more detail below, this optical signal 130 may beencoded with the video data being provided by the video source 110. Inone embodiment, the optical signal 130 contains uncompressedhigh-definition video data. Once the video data is received by receiver140, it may be decoded for display device 150.

Transmitter 200 of FIG. 2 is a more detailed diagram of one embodimentof the optical transmitter 120 of FIG. 1. Transmitter 200, whichreceives the video signal from data source 110, is depicted as includinga DVI/HDMI receiver 210, a transmitter circuit 220, a system clock 230and a transmitter electro-optical interface 240. While in oneembodiment, the data source 110 is an HDMI or DVI video source (e.g.,ATSC tuner, DVD player, etc.), it may similarly be another type of datasource.

As depicted in FIG. 2, the data source 110 provides a digital signal tothe DVI/HDMI receiver 210. The DVI/HDMI receiver 210 may be used toconvert the DVI/HDMI digital signal from the data source 110 into adigital video signal, such as 24-bit RGB. DVI/HDMI receivers are knownin the field and beyond the scope of this disclosure. In anotherembodiment, the DVI/HDMI receiver 210 and the transmitter circuit 220may be combined into a single logical circuit. While in one embodiment,the transmitter circuit 220 is a Field Programmable Gate Array (FPGA) oran Application-Specific Integrated Circuit (ASIC), it may similarly haveother implementations. The other input for the transmitter circuit 220comes from the system clock 230, which provides a clock signal. In oneembodiment, this clock signal is a 110 MHz signal. The output of thetransmitter circuit 220 is to a transmitter electro-optical interface240. One embodiment of the transmitter circuit 220 will be described inmore detail below with reference to FIG. 4, while one embodiment of thetransmitter electro-optical interface 240 is described in more detailbelow with reference to FIG. 5.

Receiver 250 of FIG. 3 is a more detailed diagram of one embodiment ofthe optical receiver 140 of FIG. 1. In this embodiment, optical receiver250, which receives the optical signal 130 from optical transmitter 120,is depicted as including a receiver electro-optical interface 260, areceiving circuit 270, a phase lock loop (PLL) 280, a DVI/HDMItransmitter 290, and a system clock 300. The optical transmitter 250 isfurther depicted as outputting video data to display device 150. Whilein one embodiment, the digital video data output to the display device150 is one of HDMI and DVI data, it may similarly be another type ofdata.

As depicted in FIG. 3, the optical receiver 250 includes a DVI/HDMItransmitter 290, the details of which are known in the field and beyondthe scope of this disclosure. In another embodiment, the DVI/HDMItransmitter 290 and the receiver circuit 270 may be combined into asingle logical circuit. As mentioned above, another input to thereceiver circuit 270 comes from the system clock 300, which provides aclock signal. In one embodiment, this clock signal is a 110 MHz signal.The transmitter circuit 270 is further depicted as being incommunication with PLL 280, which may be used to help regenerate thevideo clock of the DVI/HDMI transmitter 290.

Referring now to FIG. 4, depicted is a block diagram of one embodimentof the transmitter circuit of FIG. 2. In this embodiment, transmittercircuit 400 includes a front end 405 which may be used to receivedigital video data (such as 24-bit RGB) with control data from HDMI/DVIreceiver 210, and optional ancillary data. The front end 405 may thenoutput a near continuous stream of data to the optional RS(Reed-Solomon) Encoder 410. In one embodiment, this data is a 20-bitstream output at 110 MHz. If the incoming video data rate isinsufficient to satisfy the RS Encoder 410, null words may be generatedsuch that the RS Encoder 410 is never starved for data. In oneembodiment, the RS Encoder 410 may be comprised of two 10-bit encodersthat apply an RS code of (216,200). The RS Encoders 410 may each accept200 10-bit words of data and add 16 words of forward error correction(FEC) data. This coding scheme enables the receiver to correct up toeight errors in each RS block of 216 words. In another embodiment,forward error correction may not be performed.

The RS Encoder may then output the data to the scrambler 415, whichrandomizes the data. The scrambler 415 may randomize the data to ensurethat frequent transitions occur in the data stream. Frequent transitionshelp the receiver 270 synchronize itself to the 2.2 GHz bit clock andrecover the data. In one embodiment, the scrambler 415 may use apseudo-random number (PRN) generator to create a 20-bit random numberfor each 20-bit word. The incoming word is exclusive-OR'ed with therandom number to produce a scrambled output. As will be described below,an identical PRN generator may be used on the receiver-side tounscramble the data.

The header generator 420 may be used to output a word header. Forexample, in one embodiment, every 20 uS the header generator 420 mayoutput a 40 word header. A first portion of this header (e.g., first 20words) may be comprised of preset data used to synchronize the receiver,followed by a second portion (e.g., next 20 words) of variable data,which can include control information for the receiver-side.

The serializer 425 receives the data stream from the header generator,according to one embodiment. The serializer 425 is used to accept theencoded data in parallel and shift it out a bit at a time. In oneembodiment, the serializer 425 outputs a high rate video data stream tothe transmitter electro-optical interface 240. The clock generator 430synthesizes a clock (e.g., 2.2 GHz) used by the serializer 425 forshifting the parallel data though the system based on the clock signal435 (e.g., 110 MHz) provided by a system clock (e.g., system clock 230).2.2 GHz may be used when electro-optical system 500 is tuned to operateat this specific bit rate. A 2.2 GHz bit rate may be used because it isexactly 20 times the 110 MHz clock rate.

Continuing to refer to FIG. 4, the controller 440 may be used tosynchronize the various components of the transmitter circuit 400. Inone embodiment, it may inform the header generator 420 when to generatea header. It may also initialize the PRN generator in the scrambler 415.Moreover, the controller 440 may also start the RS Encoder 410 such thatits output will be present at the proper time. In one embodiment, thecontroller 440 may also inform the front end 405 when data must beavailable to the RS Encoder 410. In the embodiment of FIG. 4, thecontroller 440 outputs a clock to the video clock analyzer (VCA) 445.The VCA 445 may be used to count the number of video clocks per timeinterval, with the resulting count “n” being transmitted to thereceiver-side as part of the header's variable data. In one embodiment,“n” may be used on the receiver-side to regenerate the video clock.

Referring now to FIG. 5, depicted is a block diagram of one embodimentof an electro-optical system 500, which includes the transmittingelectro-optical interface 240 of FIG. 2 communicating with the receivingelectro-optical interface 260 of FIG. 3. In this embodiment, thetransmitting electro-optical interface 240 provides an optical signal550 which is received by the receiving electro-optical interface 260. Inthis embodiment, the transmitting circuit 220 provides the video signalin the form of a digital electrical signal to the laser driver 510which, in turn, generates a series of electrical potentials to the laserdiode 520. This sequence of electrical potentials is used by the laserdiode 520 to convert the signal into an optical signal 550. Moreover, acollimating lens 530 may be used to focus the optical signal 550 suchthat it is properly receivable by the receiving electro-opticalinterface 260.

A focusing lens 540 may be used to capture and focus the optical signal550 onto a photo diode 560. The photo diode 560 receives and convertsthe optical signal 550 into a digital electrical signal which may thenbe passed to a trans-impedance amp 570 and then to a limiting amp 580.

Referring now to FIG. 6, depicted is a block diagram of a particularembodiment of the receiver circuit 270 of FIG. 3. In particular, data isreceived by the receiver circuit 600 into a clock/data recovery block610 from the receiver electo-optical interface 260. In one embodiment,the function of the clock/data recovery block 610 is to extract theoriginal transmit clock (e.g., 2.2 GHz) and divide it down to reproducethe transmitter's system clock 230 (e.g., 110 MHz) for use in moving thedata through the receiver circuit 600. Moreover, clock/data recoveryblock 610 may also deserialize the data to determine where one word endsand the next begins within the serial data stream.

The header detector 620 may be used to search for the headers previouslyinserted by the transmitter circuit's header generator 420. When theheader is found, the header detector 620 may signal the controller 630to synchronize itself with the data stream. Once synchronized, thecontroller 630 may synchronize the other processing blocks in thereceiver circuit 600.

The remaining processing blocks in the receiver circuit 600 arecomplementary to those in the transmitter circuit 400 of FIG. 4. Forexample, the descrambler 640 may contain a PRN generator that isinitialized by the controller 630 at the proper time such that the datafollowing the header is restored to its pre-scrambled values. The RSDecoder 650 is used to decode the data, followed by final processing andde-multiplexing by a back-end 660, which is complimentary to thepreviously-described front end 405. In one embodiment, the backend 660is responsible for taking the data stream and extracting the originalvideo and control data.

As previously mentioned, one aspect of the invention is to provide thevideo data to the display 150 at the same resolution and with the samevideo clock speed as that of the video source 110. For example, HDMI andDVI provide a mechanism for the video source 110 to query the videodisplay 150 (sink) as to what video formats are supported. Once queried,the video source 110 may select the “best” video format for sendingvideo data to the display 150. As will be described in more detailbelow, this query communication may be performed over an I2C link.

With that said, the electro-optical system 500 has no way of knowingwhat video format will be selected by the video source 110. For thisreason, the electro-optical system 500 will be able to accommodate anyarbitrary clock rate, according to one embodiment.

While it may be possible to first convert the incoming video data to astandard format having a predetermined video clock rate, such anadditional conversion operation is undesirable due to the processingoverhead and image distortion inherent in such a conversion process.Moreover, such a system would not be able to pass HDMI data due in partto the fact that the video conversion process necessarily modifies thevideo clock which would be needed by the display to extract data-islandsin which audio information is embedded. In addition, such a system wouldnot support the HDCP scheme. If the video data is encrypted, the displaywill not be able to decrypt the data without the original video clock.

Thus, in one embodiment, the video data is transmitted from the videosource 110 through the electro-optical system 500 and to the display 150in what ever format and with the appropriate video clock, as determinedby the source 110. In one embodiment, this is accomplished byregenerating the video clock in the receiver 140. The flow of video datathrough the system is isochronous and the regenerated video clock mustbe phase-locked to the source's video clock. Video clock regenerationmay be accomplished using a video clock counter in the transmitter(e.g., video clock analyzer 445) and a special PLL (e.g., PLL 280) inthe receiver coupled to the video clock generator 680. At both thereceiver and transmitter end, the same 110 MHz clock signal is used as areference. This 110 MHz clock signal originates at the transmitter andis indirectly used to clock data across the wireless optical link. Inthe transmitter, the controller 440 divides the 110 MHz clock down tocreate a 50 kHz clock. This 50 kHz clock may then be used as a referencefor the video clock analyzer 445. In the receiver, the controller 630divides the 110 MHz clock down to create a 50 kHz clock. This 50 kHzclock is used as a reference for video clock generator 680. The videoclock generator uses the 50 kHz reference clock and the “n” value toregenerate the original video clock.

As previously mentioned, one aspect of the invention is to use a controlchannel communication system to enable content (e.g., DVI and HDMIcontent) to be transmitted wirelessly. In one embodiment, this control-channel communication system is provided by a low data-rate 2.4 GHz RFlink. Other embodiments may implement some of the control-channelfunctionality in the optical link.

In another embodiment, the RF link is used to perform required I2Cqueries of the display. I2C is an interface used to control componentsin consumer electronics. One application of I2C is HDCP (High-bandwidthDigital Content Protection) to exchange keys and other information overa DVI/HDMI cable between a source (i.e. DVD player) and a sink (i.e.display). I2C is a memory-bus-like protocol used over two wires tocontrol components in consumer electronic systems. A master, such as amicrocontroller, can write commands and read status from registerlocations in one or more slave devices. Buffering devices permit wiredextensions but the memory bus nature of the protocol make real-timewireless extension difficult. Converting the connection to wirelessrequires preserving real time response with minimal data transferlatency.

Referring now to FIG. 7, depicted is one embodiment of how acontrol-channel communication system 700 may be implemented. In thisembodiment, a master 710 communicates wirelessly through slave simulator720, while a slave device 750 communicates wirelessly through mastersimulator 740. In one embodiment, the master is the transmitter 120,while the slave 750 is the receiver 140. Moreover, the components whichcomprise the slave simulator 720 and the master simulator 740 may beintegrated, in whole or in part, with the transmitter 120 and receiver140, respectively. Moreover, while in one embodiment wireless link 730is a 2.4 GHz RF link, it should similarly be appreciated that it may beany other type of wireless link.

With writes from the master 710 to the slave 750, address and datainformation are simply relayed with a minimum of overhead. This involvescapturing the writes with appropriate handshakes, wrapping the contentinto the wireless protocol, and reconstituting the write operation onthe receiving side. In one embodiment, this may be implemented as a“store and forward” operation starting with the slave simulator 720receiving the command, then passing it over the link to the mastersimulator 740, which in turn sends it onto the slave 750. A fewmilliseconds end-to-end delay may be introduced, but all protocol timingis met.

I2C reads expect immediate response. There is not sufficient time tosend the read command over the link followed by return of the desireddata. Thus, in one embodiment, a shadow memory may be used on each side.These memories may mirror what is found in the slave device registers.The slave side of the link may poll the device registers and maintain alocal shadow copy. When a change of data is noted, updates may be sentover the link 730 to the master side shadow. This data may then beavailable to the master 710 on demand. In this manner, all I2C protocoltiming is maintained and the master 710 has no idea it is not accessingthe real device.

In another embodiment, shadow memory in the slave simulator 720 may beimplemented as a dual port RAM and kept current by the master simulator740. Any changes in the actual device data may be noted by the mastersimulator 740 with updates sent to the slave simulator 720.

As previously mentioned, a second shadow memory may be maintained in themaster simulator 740 attached to the actual slave device 750. It may beused to store the reference values for determining when slave data haschanged. The master simulator 740 may keep both memories current bypolling the slave 750 through, for example, all possible sub-addressesor, alternatively, only touching the ones known to be volatile.

While the invention has been described in connection with variousembodiments, it will be understood that the invention is capable offurther modifications. This application is intended to cover anyvariations, uses or adaptation of the invention following, in general,the principles of the invention, and including such departures from thepresent disclosure as come within the known and customary practicewithin the art to which the invention pertains.

1. A combination wireless optical and radio frequency communicationsystem comprising: a transmitter, coupled to a video data source havinga source output, the transmitter comprising an optical wirelesstransmitter to receive video data from the source output and to encodethe video data into a laser beam, the transmitter further comprising areceiver simulator having a first shadow memory, and wherein thetransmitter further comprises an associated first radio frequencytransceiver for sending a query for video format information, and forreceiving, in response to the query, video format informationcorresponding to a preferred format of the display device; and areceiver, coupled to a display device, the receiver comprising anoptical wireless receiver to receive the laser beam and to decode thevideo data therefrom, the receiver further comprising a transmittersimulator configured to, poll one or more device registers of a displaydevice and send updates to the first shadow memory of the receiversimulator for access by the transmitter upon request, where said updatesare based on information obtained from said polling of the one or moredevice registers.
 2. The system of claim 1, wherein the transmitter andreceiver engage in two-way communication over a control-channel radiofrequency communication link to exchange encryption information tosatisfy one or more digital interface queries.
 3. The system of claim 1wherein the transmitter simulator includes a second shadow memory formaintaining a local copy of the one or more device registers.
 4. Thesystem of claim 3, wherein the receiver and transmitter simulators, byvirtue of having the first and second shadow memories, respectively,enable the transmitter and receiver to wirelessly communicate whilestill maintaining required protocol timing.
 5. The system of claim 1,wherein the optical wireless transmitter is to encode said video datainto a laser beam in accordance with the received video formatinformation.
 6. The system of claim 5, wherein the receiver furthercomprises an associated second radio frequency transceiver for receivingsaid query and for sending, in response to the query, requested videoformation information to the first radio frequency transceiver.
 7. Asystem comprising: a transmitter, coupled to a video data source havinga source output, said transmitter having an associated first radiofrequency transceiver for sending a query for video format information,and for receiving, in response to the query, video format informationcorresponding to a preferred format of a display device, wherein thetransmitter further comprises an optical wireless transmitter to receivevideo data from the source output and encode said video data into alaser beam in accordance with the received video format information; areceiver, coupled to a display device, having an associated second radiofrequency transceiver for receiving said query and for sending, inresponse to the query, requested video formation information to thefirst radio frequency transceiver, wherein the receiver furthercomprises an optical wireless receiver to receive said laser beam and toextract said video data therefrom for presentation by said displaydevice; a receiver simulator coupled to the first radio frequencytransceiver having a first shadow memory; and a transmitter simulatorcoupled to the second radio frequency transceiver, wherein thetransmitter simulator is configured to poll one or more device registersand send updates to the first shadow memory of the receiver simulatorfor access by the transmitter upon request, where said updates are basedon information obtained from polling of the one or more deviceregisters.
 8. The system of claim 7, wherein said optical wirelesstransmitter includes a laser diode and a collimating lens, and whereinsaid laser beam is generated using said laser diode and then directedusing said collimating lens.
 9. The system of claim 7, wherein saidoptical wireless receiver includes a focusing lens and a photo diodeusable to receive said laser beam.
 10. The system of claim 7, whereinsaid video data is transmitted from said optical wireless transmitter tosaid optical wireless receiver at a rate of approximately 2.2 Gbps. 11.The system of claim 7, wherein said optical wireless receiver is furtherto recover a video clock signal from said video data, wherein said videoclock signal is generated by the optical wireless transmitter andencoded into said video data.
 12. The system of claim 7, wherein saidvideo data has forward error correction encoding applied to correcterrors caused by sending said video data from said optical wirelesstransmitter to said optical wireless receiver.
 13. The system of claim7, wherein the first and second radio frequency transceivers areconfigured as a control-channel radio frequency communication link toenable said video data source to exchange information with said displaydevice.
 14. The system of claim 7, wherein said video data source anddisplay device exchange encryption information over said control-channelradio frequency communication link to satisfy one or more digitalinterface queries.
 15. The system of claim 7, wherein the receiversimulator is integrated with the first radio frequency transceiver, andthe transmitter simulator is integrated with the second radio frequencytransceiver.
 16. The system of claim 7, wherein the transmittersimulator includes a second shadow memory for maintaining a local copyof the one or more device registers.
 17. The system of claim 16, whereinthe receiver and transmitter simulators, by virtue of having the firstand second shadow memories, respectively, enable the transmitter andreceiver to wirelessly communicate while still maintaining requiredprotocol timing.
 18. A method comprising: receiving video data from asource having a source output; sending a query for video formatinformation over a control-channel radio frequency communication link;receiving over the control-channel radio frequency communication link,and in response to said query, video format information corresponding toa preferred format of a display device; encoding said video data into alaser beam in accordance with the received video format information;transmitting said laser beam from an optical wireless transmitter to anoptical wireless receiver; receiving said laser beam by the opticalwireless receiver to extract said video data therefrom; providing saidvideo data to a display device having a destination input; polling oneor more device registers of the display device; and sending updatesbased on said polling over the control-channel radio frequencycommunication link to a first shadow memory local to the source foraccess by the source upon request.
 19. The method of claim 18, whereintransmitting said laser beam comprises transmitting said laser beamusing a laser diode and a collimating lens of the optical wirelesstransmitter.
 20. The method of claim 19, further comprising generatingsaid laser beam using said laser diode, and directing said laser beam tosaid optical wireless receiver using said collimating lens.
 21. Themethod of claim 18, wherein transmitting said laser beam comprisestransmitting said laser beam from the optical wireless transmitter tothe optical wireless receiver, wherein said optical wireless receiverincludes a focusing lens and a photo diode usable to receive said laserbeam.
 22. The method of claim 18, wherein transmitting said laser beamcomprises transmitting said laser beam from said optical wirelesstransmitter to said optical wireless receiver at a rate of approximately2.2 Gbps.
 23. The method of claim 18, further comprising: measuring avideo clock signal by the optical wireless transmitter to provide avideo clock measurement; and encoding said video clock measurement intosaid video data.
 24. The method of claim 18, further comprisingrecovering said video clock signal from said video data using saidoptical wireless receiver.
 25. The method of claim 18, wherein saidsource output and display device exchange information over saidcontrol-channel radio frequency communication link to satisfy one ormore digital interface queries.
 26. The method of claim 18, furthercomprising applying forward error correction to said video data tocorrect errors caused by said transmitting said laser beam from theoptical wireless transmitter to the optical wireless receiver.
 27. Themethod of claim 18, further comprising storing data from the one or moredevice registers in a second shadow memory local to the display device.28. The method of claim 18, wherein the control-channel radio frequencycommunication link enables wireless communication between the source anddisplay device in accordance with required protocol timing.